The World Reference Center for Arboviruses identifies and characterizes viruses suspected of being biologically transmitted by arthropods as well as certain other viruses similar in some respects to arboviruses. A collection of nearly 400 already characterized reference viruses and sera is utilized in the neutralization, complement-fixation, hemagglutination-inhibition and immuno-fluorescence tests to determine the relationship of referred viruses to the reference viruses. Physical and morphological characteristics of selected new arboviruses are determind by electron microscopy and polyacrilamide gel electrophoresis. The collection is also used for serologic diagnosis of disease, study of epidemics and seroepidemiologic surveys. This collection of reference arboviruses is the only complete collection in the world. The long-term aim is to develop new research areas and research models in virology and epidemiology as has been done in the past with Congo-Crimean hemorrhagic fever viruses, rabies-related viruses, tick-borne orbiviruses of Ixodes uriae, insect viruses (Baculoviruses) and insect cell cultures.